feat(emails): add re-send for all emails, failed tab, and resend indicators

- Add resend_attempts and last_resent_at to email_logs schema and migrations
- Add POST /api/emails/logs/:id/resend and emailService.resendFromLog
- Add resendLog API and EmailLog.resendAttempts/lastResentAt
- Add All/Failed sub-tabs, resend button for all emails, re-sent indicator in logs and detail modal

Made-with: Cursor

backend/src/routes/emails.ts

@@ -349,6 +349,23 @@ emailsRouter.get('/logs/:id', requireAuth(['admin', 'organizer']), async (c) =>
   return c.json({ log });
 });
 
+// Resend email from log
+emailsRouter.post('/logs/:id/resend', requireAuth(['admin', 'organizer']), async (c) => {
+  const { id } = c.req.param();
+  
+  const result = await emailService.resendFromLog(id);
+  
+  if (!result.success && result.error === 'Email log not found') {
+    return c.json({ error: 'Email log not found' }, 404);
+  }
+  
+  if (!result.success && result.error === 'Email log missing required data to resend') {
+    return c.json({ error: result.error }, 400);
+  }
+  
+  return c.json({ success: result.success, error: result.error });
+});
+
 // Get email stats
 emailsRouter.get('/stats', requireAuth(['admin', 'organizer']), async (c) => {
   const eventId = c.req.query('eventId');